What should never be introduced to a pumper that is being supplied from a hydrant?

A pumper should never be introduced to contaminated water because such water can compromise the integrity of the fire apparatus systems, damage firefighting equipment, and pose health risks to personnel. Firefighters depend on the pumper and its components to deliver a clean and effective firefighting agent. If contaminated water is used, it can introduce harmful materials into the pump and hoses, leading to potential failures or hazardous situations during emergency response.

Using pressurized water from another source could be potentially acceptable in certain scenarios with proper precautions, while static water typically refers to the storage of water in a tank, which can be used during firefighting. Excessive volumes of water should be managed to prevent overloading the pumper, but they don't pose a direct risk as contaminated water does. Therefore, the focus should always be on ensuring the water quality supplied to the pumper to maintain operational effectiveness and safety.